On Sat, Jan 31, 2009 at 8:09 AM, mabshoff <[email protected]> wrote:
>
>
>
> On Jan 31, 7:31 am, William Stein <[email protected]> wrote:
>> On Fri, Jan 30, 2009 at 6:22 PM, mabshoff <[email protected]> wrote:
>
> <SNIP>
>
>> > I just did extend my little script to also detect SSE2 instructions
>> > and only in $SAGE_LOCAL/lib there are 43 static libs and 143 dynamic
>> > libs which use SSE2, so in so many words "No way José" without massive
>> > poking around in the build system.
>>
>> I'll let  José know that he's out of luck.
>
> Well, I thought about this again and the above numbers are on a 64 bit
> system where SSE2 is guaranteed to be available. So any non-SSE2, SSE
> only binary would make only sense on a 32 bit x86-ish CPU.
>
>> Have you tried detecting pni, sse4_1 and cmov (the other flags we test for)?
>
> pni ==  SSE3 (Prescott New Instricutions), we don't use SSE4_1 yet in
> Sage. There is a branch of MPIR that uses SSE4a instructions, but we
> will build MPIR with --enable when that code is merged anyway.
>
> cmov has been around since the days of the Pentium Pro and testing for
> it back in the day made sense since IIRC there was some Cyrix "Pentium
> Pro class" CPU which did not have cmov.
>
> I would suggest we introduce something like
>
>  SAGE_OPTIMIZATION_TARGET
>
> and if it is set to SSE2 (which for now is the only valid setting) we
> build ATLAS with SSE2 only. The tuning will still be shitty for other
> CPUs since sage.math's caches are rather above average in size, but I
> guess a working binary is better than a slightly faster, but crashing
> binary :)
>
> I can add that env flag into the ATLAS.spkg in 3.3.alpha4 since I need
> to fix some Solaris SNAFU I introduced anyway.
>
> Thoughts?

+10

Fixing these cpu flag issues will make a lot of people's lives much simpler.

William

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